Place them by a sunny window- we place some in our 3-season porch with the dome lid on to retain more moisture and so the seedlings won’t freeze.

Growing 💡: While your seedlings are indoors, an oscillating fan can be used to mimic an outdoor breeze to promote stronger, straighter stems.

Alternative Plant your Milkweed Seeds

If you use the seed starter trays, you could transplant the seedlings into a new winter sowing container. In Minnesota, I’ve kept ours in the 3-season porch (with lid secured!) until about St. Patty’s Day, then moved containers outside. On nights well-below freezing, they’re moved into the garage or house.

Once the threat of frost is over, remove the lid and let the seedlings grow until it’s time to transplant.

Why does heat matter?

Since the seeds germinate at around 75° F, northern germination outdoors might not occur until late June or July. This gets your annual milkweed plants off to a super slow start and then, before you know it, their fate is sealed by a Game of Thrones…Winter is Coming.

I foolishly believed that heated seedling mats were a “marketing ploy” in my early days of gardening. Once I broke down and bought one, I was simply amazed by the results. Not only did my seedlings sprout in record time, I also had my highest germination rate ever for tropical milkweed.

While spring sowing tropical seeds might be easier, what’s the point if these are the measly results:

Teeny Tiny Tropical…Late August!

This late-August tropical milkweed plant started from seed in a local butterfly garden. Even with the encouragement of soaking rains and sizzling summer sun, it never grew up to share nectar with a monarch, or feed hungry caterpillars.

For annual milkweed, starting seeds indoors can mean the difference between a long summer of beautiful blooms with butterflies, or the joyless alternative above. I know what I’m choosing…

Note: While starting seeds indoors is a fantastic option for starting your annual milkweed supply, it’s much easier to continue that supply by taking yearly milkweed cuttings in fall or winter.

In my next post, I’ll discuss how to proceed once your milkweed seeds have sprouted.

Comments

I agree that heating mats are one of the best ways to germinate seeds and coax roots from cuttings. Naturally, I use them on my tropical seeds, and use a mat on my native milkweeds also after stratifying them in the reefer for six weeks.

Even here in sunny SoCal a mat gets things going MUCH sooner than relying on spring to arrive. I start my seeds in December. by March they go outside six to eight inches tall on some species!

I had just bought tropical milkweed plant from eBay five min. Ago and realized that I don’t know what to do with a dormant plant. Anysuggestions would be appreciated. I bought the plant because I don’t have any luck germating seeds. I’ve tried in the past and just ended frustrated.

Hi Helen,I’m assuming you want them to come out of dormancy now? You could put them near a window or even put grow lights or CFL lights on them so they break dormancy. If you want them to stay dormant you could always stick them in a cool basement or garage. If you don’t want dormant plants, you could also try canceling your order. Hope this helps, Tony

We want to start growing some tropical and balloon milkweed seeds inside, but I’m a little confused on the timing of when to start the seeds. From the dates on your post, it looks like you are starting your annual milkweeds in February.

Here in Michigan, the date that everyone throws around for planting annuals is typically Memorial Day, maybe a little earlier if the weather is nice. If I was to start my seeds in February, I would be afraid that my balloon plants would be three to four feet tall before I even planted them outside?

Am I reading the post correctly? Have you started growing your 2015 annual milkweed plants already? Do you move your plants outside in early May if the weather is nice? Thanks for any advice on when to start annual milkweeds from seed.

Hi Brian, 2 months before planting should give you all the head start you need. I started seeds early this season because I unsure of seed viability.

I’m also trying some experiments so I can help you and the community start milkweed seeds with the highest germination rate possible.

It really doesn’t matter how big your balloon plants are, if you have the room to let them get that large. The one concern would be if they had weak stems and started leaning over. An oscillating fan really helps with that though. I’ll be reporting more on seed-starting the next couple weeks…

Hi Tony, I have a ton of tropical milkweed seeds to plant, I’m hoping for a good turnout! I live in South Florida, as you can imagine the weather is already very warm (80s). Do you think I could grow my seedlings on the back lanai? Or am I better off growing them inside? Thank you! Danielle

I just received my milkweed seeds from Monarchwatch. It said on the packet to use cold stratification.th the seeds and It is April 29 and our last frost is the end of May. We are planting a Monarch Garden at our school and want to be ready by the last frost. Two questions: What should I do now and will they be ready in enough time for the Monarchs? Would I be better off buying some plants?

I got an order of Oxypetalum caeruleum seeds from GeorgiaVines and am ready to start them but am having some trouble figuring out the best way to plant them. I followed your advice on presoaking seeds for my Tropical Milkweed and they are doing great. I am considering pre-soaking the Tweedia, too. Will that work for them as well? I have gotten some conflicting info on how to start them. Do i really need “starting soil” for them? I used empty metal cat food/tuna cans filled with potting soil for my Tropicals in order to transfer heat to the soil easier. I’m in Tampa Florida so i’m going with no cold stratification. All of this is going in my little outdoor greenhouse. so far its all doing great. I also have a Balloon plant also that’s been supporting all the Cats and as they get big we are bringing them in to Chrysalis. I’ve eclosed 4 so far! Anyways, any advice on the Tweedia will help as I only have 10 seeds and want to do my best with them! Thanks for all the info on the site….its GREAT!

Hi Tom, you would use the same soaking method that you used for tropical milkweed seeds. You don’t need seed starting soil if you are starting them outside. Keep in mind, I’m a Minnesota gardener so we take some extra steps so we don’t get too far behind!

Hi all, Interesting to read about the problems you are experiencing regarding climate.Something I would like to add for those of you interested in establishing a “Butterfly Garden” is the notion of companion plants. For the past three or four years we have noticed Monarchs over-wintering in our garden here in New Zealand.Our winters are relatively mild by Northern Hemispheric standards-typically in the 30 to 60F range. We have around 100 or so butterflies flitting around the garden at the moment–either in a big eucalyptus tree or in the nearby Lacebark (https://www.google.co.nz/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=lacebark%20tree%20nz) or in the Callistemon (Bottlebrush); both these trees have flowers that attract the butterflies and seem to sustain them over the winter months. As well as planting as many swan plants as possible(and keeping some guarded in reserve) I reccomend a longer term view of providing these ‘companion’ trees/plants in climes where suitable.The further south you are in USA eg the better chance you would have to keep the butterflies coming back!

Hi Ged, thanks for your post. Keep in mind, the eastern monarch population in North America migrates to Mexico. If they stayed in the southern US there would be increased disease due to overused milkweed. In regions like south Florida and southern California where there are monarchs year-round I know there are eucalyptus trees (west coast) and bottlebrush is big in Florida. More gardeners across North America are planting swan milkweed and we even have some growing in our northern garden. I agree having a wide variety of milkweed keeps the monarchs coming back…

My giant milkweed was up in 3 days. Did not use saltpeter this year. Tropicals coming up today, 5 days. The trick is to give them a warm bath overnight. I keep everything at 85 degrees or so. Most of the seeds had sprouted in 24 hours. Don’t be cheap, go to the garden center and pony up for a heat mat, cells and a dome. Will last for years. 20 bucks or so. Beats making your own and a lot faster. And you do not have to look like a hillbilly when your fellow gardeners come over to see your project.

This morning 3 Monarchs emerged here inside. The weather doesn’t permit me to release for another 4 days. (40 degrees). My milkweed won’t last long for the 20 cats that I’m raising .BUT!! I want you and others to know that I purchased 2 quarts of milkweed yesterday at Lowes. Today I found my cats turning black and not eating! Called my local nursery..THESE PLANTS are poisonous because the plants are raised with Pestacide. I lost 7 or 8 different sized cats that were 100 percent healthy. Just a warning!!! Buy good milkweedat Walmart! To change the subject, can I used a water soaked cotton ball for new Monarchs to drink while waiting for the temperature to warm up here in Tampa??? Please advise..I’m desperate and don’t want to lose them!!

Hi Babs, there’s always a risk buying from big box stores because many still buy from growers that use pesticides. If your caterpillars turned black, this is a common sign of disease (which could also be from the new milkweed source).

Dear Mr. Gomez, forgive me for I have sinned. It’s because of ignorant people like me, the Monarch Butterfly isn’t population is not flourishing! Very, very long story short; I was given a plant without knowing what it was 2 years ago. This year the plant thrived but many orange aphids and caterpillars. In keeping the plant healthy I killed all the pesky aphids “AND CATERPILLARS” found on my plant daily. Yesterday I finally found the time to research what the plant is and learn the recommended pest control was, needless to say I was horrified to learn what a jewel I had and what a horrible crime I’ve been committing the past months. I’m more than anxious to start raising the Monarch’s next year, and as I discovered last night you are surely the expert. My question to you is: where should I start learning? You have hundreds of fascinating articles…can you recommend where to begin? Thanks!

This year will be my first attempt at growing milkweed. I live at the edge of a marsh in south central Wisconsin. I hope to attract monarch butterflies. I have started outside about 25 jugs with various types of milkweed and others that need the cold process. I purchased several kinds of tropical milkweed seeds and am starting those indoors. I have 2 heating mats but that will not be enough for my needs. They can be a little pricey.

In my basement I have radiant floors. They are not turned on and the air temp is about 65 degrees. Do you think I could put the plants on the floor and turn on the heat and that would make a giant heat mat? I have several grow lights hanging from the ceiling as I have some other plants overwintering there (they are starting to come out of hibernation).

I am new to butterflying , but am hooked. I live in north western Wisconsin. I have seeds from our local milkweed but would like to try a couple of other kinds hearty to my area. What would you suggest?

Just added a heated seedling mat with freshly planted Tropical milkweed seeds. I noticed that there is a lot of condensation on the clear cover. I didn’t have this problem before the heated seed mat. Should I poke vent holes in the cover or is it okay to for the extra moisture?

I live in Northern Ohio. I started my common and tropical milkweed a couple weeks ago. I don’t use a heating mat, but I place the racks of plants in front of my soyth-facing sliding doors. The sun radiates through and keeps things nice and warm … I actually have to monitor yo make sure they don’t get too jot at times! This year I had germination in 4 days! Seedlings are now between 3 and 4 inches tall with true leaves. So excited for the season!!